Modern aircraft, such as large passenger jets, need to operate at various speeds, including a lower speed during take-off and landing and higher speed during cruise. To accommodate operations at the various speeds, the aircraft wings include control surfaces. Typically, the control surfaces are actuatable relative to a fixed portion of the wing. By changing positions of the control surfaces relative to the fixed portion of the wing, various aerodynamic effects are achieved. The aerodynamics effects are used to control the aircraft.
One type of control surface is a spoiler. Often, spoilers are mounted adjacent to and in front of the wing flaps on a wing such that the spoilers cover a portion of the wing flaps. The spoilers can be designed to extend upwards into the air flowing over the wing in flight. When extended, a controlled stall is created over the portion of the wing behind it, which reduces the lift of that wing section and increases drag. One benefit of deploying spoilers is that the descent rate of the aircraft is increased without increasing speed.
At landing, the spoilers can be fully deployed upwards once the airplane touches down. The increase in drag adds to the braking effect. In addition, the loss of lift transfers more weight to the wheels which aids in the mechanical braking process.
During takeoff and climb as well as upon approach during landing the spoilers and droop panels can be retracted downwards towards the extended flaps to control and optimize the gap between flap and spoiler. For spoilers this is achieved by actuation. For slaved droop panels this is achieved by mechanically linking the panel to the mating flap or flaperon.
At cruise conditions, the spoilers are generally not deployed and are positioned such that the spoiler surface and flap surfaces form an aerodynamic shape with the best aerodynamic performance. However, under aerodynamic loads at cruise conditions, the wings, flaps and spoilers all deform. The mismatch in the deformations can cause geometry variations that reduce aerodynamic performance of the wing. For example, gaps can form between a spoiler and a flap or between adjacent spoilers, which allow air flow into the wing trailing edge cavity. Additionally, mismatch between spoilers or between spoilers and flaps result in excrescence drag. This undesirable airflow and mismatch reduces the aerodynamic performance of the wing. In view of the above, methods and apparatus are needed that reduce geometry variations associated with the spoilers as a result of different loading and structural conditions during flight.